> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cowboy.inc/llms.txt
> Use this file to discover all available pages before exploring further.

# E1209 — Sandbox violation (forbidden syscall)

> Sandbox violation (forbidden syscall)

# E1209 — Sandbox violation (forbidden syscall)

| Property | Value |
| - | - |
| **Code** | `1209` |
| **Slug** | `E1209` |
| **Category** | `runtime` (Runtime) |

## What happened

Sandbox violation (forbidden syscall).

This is the receipt's `what` text, produced by the host-call result `HostError::SandboxViolation`.

## Why it happened

The node rejected the operation with `E1209` (category `runtime`, Runtime). The receipt's `why` field carries the specific cause and `context` carries structured details, when the emitter attaches any.

## How to fix

The actor attempted a syscall the PVM sandbox forbids (deterministic seccomp kill). Remove the disallowed operation (filesystem/network/subprocess/etc.) from the handler.

## Receipt example

```json theme={null}
{
  "code": 1209,
  "slug": "E1209",
  "category": "runtime",
  "what": "sandbox violation (forbidden syscall)",
  "fix": "The actor attempted a syscall the PVM sandbox forbids (deterministic seccomp kill). Remove the disallowed operation (filesystem/network/subprocess/etc.) from the handler.",
  "docs_url": "https://docs.cowboy.inc/errors/E1209"
}
```

***

> [card] [All Error Codes](https://docs.cowboy.inc/errors/overview.md)
>
> View the complete error code reference


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